End cap for the fluid impregnation of timber

ABSTRACT

An apparatus for longitudinal fluid impregnation of a log comprising a cap for enclosing one end of a log, the cap having a rear wall and a peripheral side wall so as to define a fluid treatment zone, members inserted through apertures in the side wall of the cap for locking it to the log, a first ring for encircling the log and abutting the said members, a self-sealing compressible means for encircling the log and abutting the first ring, a second ring for encircling the log and abutting the sealing means, the second ring having or associated with means for retaining it against movement on the log, means for exerting pressure on an end of the log so that compression will be applied to the sealing means, and means for introducing a pressurised log-treating fluid into the treatment zone for the fluid to be forced along within the log.

United States Patent Mason [76] Inventor: Cecil George Willmot Mason, Hwy.

60 Mapua, RD. 1, Upper Moutere, Via Nelson, New Zealand [22] Filed: June 27, 1973 [21] Appl. No.: 374,072

[30] Foreign Application Priority Data July 3, 1972 New Zealand 167652 [52] US. Cl 21/72; 21/7 [51] Int. Cl 827k 3/10; B27k 5/02 [58] Field of Search 21/72, 68, 71, 7, 62, 63; 117/117; 144/257, 309 Y, 327, 324, 317

[56] References Cited UNITED STATES PATENTS 771,689 7/1903 Willner 117/117 803,603 12/1905 Kron 1. 21/71 1,259,025 3/1918 Kennedy et al n 21/68 3,427,186 2/1969 Hudson 21/72 3,443,881 5/1969 Hudson 21/68 May 20, 1975 Primary Examiner-Morris O. Wolk Assistant Examiner-Bradley R. Garris Attorney, Agent, or FirmGottlieb, Rackman, Reisman & Kirsch [57] ABSTRACT An apparatus for longitudinal fluid impregnation of a log comprising a cap for enclosing one end of a log, the cap having a rear wall and a peripheral side wall so as to define a fluid treatment zone, members inserted through apertures in the side wall of the cap for locking it to the log, a first ring for encircling the log and abutting the said members, a self-sealing compressible means for encircling the log and abutting the first ring, a second ring for encircling the log and abutting the sealing means, the second ring having or associated with means for retaining it against movement on the log, means for exerting pressure on an end of the log so that compression will be applied to the sealing means, and means for introducing a pressurised logtreating fluid into the treatment zone for the fluid to be forced along within the log.

15 Claims, 8 Drawing Figures PATENTEB MAY 2 0 I975 SHEET 2 OF 3 END CAP FOR THE FLUID IMPREGNATION OF TIMBER This invention relates to apparatus and processes for end impregnation of green" round timber such as logs, poles and the like (hereinafter generally termed log) with a fluid which imparts a desirable property to the log thus impregnated, such as preservation against decay and attack by insects, fire retardation. dimensional stability by chemical reaction or physical process and such like.

Processes for end impregnation of logs have been known for many years but even though many such processes have been tested on a commercial scale they have several drawbacks mainly lying in deficiencies in the apparatus employed for the carrying out of the process. This has led to much development work on a suitable apparatus through which the desired fluid can be forced under pressure into one end of the log with or without supplementary suction apparatus operating at the other end of the log. Such apparatus to be of commercial value under present day conditions is required to withstand pressures of up to 14 kg/sq.cm and suitable for treating sizes ranging from the smaller logs such as fence posts up to the larger whole tree trunks which can reach diameters of 24 inches and more. The commercial feasibility of impregnating logs at such high pressures mainly depends of the devising of a satsifactory apparatus, in particular a pressure cap for introducing the impregnant into the end of a log.

Such a cap should have the following features:

a. The attaching and removing of the cap to the log should not take too long,

b. In fitting the cap to a log the sealing means should be so designed as to be leakproof against impregnating the log with fluid at pressures up to 14 kg/sqcm.

c. Design of cap and other equipment should be such that initial cost and cost of maintenance are minimal.

Heretofore the problem of completely eliminating leakage of the fluid from an apparatus fixed about the surface at one end of the log has not been successfully overcome. One proposal has been the provision of a resilient annular ring passing tightly about the log and compressed between retaining rings, such compression having been effected by manually operable means such as screw-threaded bolts acting on one of the retaining rings. However, the problem of leakage of the solution still existed as the sealing effect of the resilient annular ring was limited by the degree of tightness exerted by the screw-threaded bolts. Also the means of retaining the cap on the end of the log against the force exerted in the cap by the impregnating fluid is by means of spikes inserted into the log through the side of the cap near its open end and hence beyond the gland system. Insertion of these spikes into the log requires considerable force and takes time but more importantly the spikes penetrate the longitudinal conducting system of the log and thus inevitably create zones of solution leakage at each spike penetrating region. Other disadvantages are complicated. heavy and expensive apparatus. Ease and quickness of fitting of the cap is, as stated under (a) above, important. In addition every tree is different in butt diameter hence it is important that caps can be used on trees having a range of butt diameters.

The present invention is therefore concerned with an apparatus for treating fluid impregnation through the end of a log in which a sealing means provides a seal not subject to leakage as has occurred in the apparatus such as previously mentioned and is simple and effective. The invention is further concerned with the provision of a process of treating a log by fluid impregnation in which positive simple and effective seal is afforded.

In one aspect the invention consists of an apparatus for longitudinal fluid impregnation of a log comprising a cap for enclosing one end of a log, the cap having a rear wall and a peripheral side wall so as to define a fluid treatment zone, members inserted through apertures in the side wall of the cap for locking it to the log. a first ring for encircling the log and abutting the said members, a self-sealing compressible means for encircling the log and abutting the first ring, a second ring for encircling the log and abutting the sealing means, the second ring having or associated with means for retaining it against movement on the log, means for exerting pressure on an end of the log so that compression will be applied to the sealing means, and means for introducing a pressurised log-treating fluid into the treatment zone for the fluid to be forced along within the log.

Under this aspect the first ring, the sealing means and the second ring are to be located on the log from the locking members, towards that end of the log to be located within the cap and the means for exerting pressure of the end of the log is of a nature whereby a member is activated by pneumatic, hydraulic or mechanical pressure.

Again under this aspect, the first ring, the sealing means and the second ring are to be located on the log from the locking members. away from that end of the log to be located within the cap and sub-atmospheric pressure is applied to the other end of the log.

One feature of the apparatus is the sealing means with a sealing ring made of a resilient material having a certain ratio of elasticity to ductility. The desired properties of the material are that it is resilient to compression but it is of sufficient elasticity to stretch and fill entirely the space which it occupies. The form of the sealing ring is preferably W" cross-section as later mentionedv Another feature is the second ring being associated with the retaining means consisting of a chain, the chain having a length so that it can be passed around the girth of a log and having locking means so that the chain is secured tightly on the log.

According to another aspect the invention consists of a process of treating a log by fluid impregnation wherein a first ring and then a sealing means is passed to encircle the log inwards from its end, a second ring is then passed to encircle the log and retained to the log behind the said sealing means, an end cap having a rear wall, a peripheral side wall and a log-end pressure applying means is passed to enclose the log end, the rings and the sealing means, to define a treatment zone between the log, the sealing means and the end cap, members are then inserted through apertures in the peripheral wall of the end cap to lock the cap on the log and to prevent backward movement of the rings and the sealing means in the cap, inserting pressure to the end of the log end and finally introducing a pressurised log treating fluid into the said treatment zone, for the fluid to be forced along within the log.

In further describing the invention, reference will be made hereinafter to the accompanying drawings, in which:

FIG. I is a part-sectional side view of the cap shown mounted on one end of a log,

FIG. 2 is a part-sectional end view of the cap;

FIG. 3 is a sectional view through part of the cap showing a locking member for the first ring and FIG. 4 is a plan thereof;

FIG. 5 is a sectional view through an air release valve;

FIG. 6 is a sectional view through a log displacement means;

FIG. 7 an elevation showing a locking means for the chain to the log and FIG. 8 is a plan thereof.

In giving effect to the invention the cap 10 consists of a rigid, impermeable outer pressure vessel of substantially half spherical closed end being the rear wall and a cylindrical body being its peripheral side wall. The other end of the cap is thus open. The cap 10 has a cylindrical body 11 with a domed end 12. For lightness in handling and ease of construction the cap 10 is moulded in fibreglass with diameters up to 250 cm. Larger caps are more economically made in steel. Moulded into the domed end l2 of the cap 10 is a hydraulic ram 13 and fluid line inlet and outlet connections 14. Also moulded into the cap 10 near its open end are floating ring retaining pins 15 and near the domed end 12 of the upper side of the cap disposed on a vertical axis an air release valve 16.

The gland system comprises of the first ring consisting of a floating split ring gland plate 17, the sealing means consisting of an elastomer gland 18, the second ring consisting of a fixed split ring gland plate 19 and the retaining means consisting of a linked chain 20.

For I50 cm internal diameter caps high tensile strength fibreglass-polyester resin 6 mm thick permits application of pressure up to 14 kg/sgcm (200 lb/in The cap interior must be smoothly and accurately circular. The components 13-15 are securely sealed into the cap during moulding.

The hydraulic ram 13 has a piston 21 sealed by 0- rings 22 which slides in a cylinder 23 attached to the cap 10. The piston stroke is 50 cm. The piston 21 is actuated by the impregnating fluid pressure applied through one of the connections 14 in the outer end of the ram cylinder. The other similar connection 14 admits impregnating fluid to the bottom of the cap 10 through a line 24 ending in a gauze filter 25. Fluid is also withdrawn from the cap through this line (24).

The air release valve 16 has a float 26 sitting on a ring 27. The float 26 is in the open position until the liquid has entered the cap I0 to a level where the air is expelled. The float 26 is so balanced that when it is immersed in the liquid it rises to sit on the ring 27, thus closing the valve and allowing the build up of full hydraulic pressure. The float 26 is positioned slightly below the inside surface of the cap 10 so that the valve 16 shuts before the fluid in the cap 10 reaches the valve seat. This avoids the escape of even a small amount of fluid through the valve 16. A gauze filter 28 is placed on the liquid side of the valve 16 so that any floating solid matter on the surface of the liquid is prevented from possible obstruction of the valve system.

The chain acting as a gland ring anchor, is sufficiently long to permit it to be wrapped around the log, to cm, from the log end. The chain 20 is firmly clamped on to the log by a tightening device 29 designed for quick and secure anchoring of the chain 20 into the log surface.

To explain in further detail the pressure cap 10 has towards its open end a series of the log-locking pins 15 arranged substantially in a plane around the circumference of and removably passing through apertures located near the open end of the cap. Generally for a normal sized log of 150 cm to 250 cm in diameter, four to six such pins 15 are provided evenly spaced around the cylindrical cap and in the same plane at right angles to the longitudinal axis of the cap. Such pins 15 are of a strong construction such as bayonet screws 30 with spring release, preferably arranged so that it requires a turn for log securing and a similar opposite turn for log-release, so that quick securing and release actions are achieved. These screws 30 are rigidly held at right angles to the cap and extend inward to slidably contact the log. As an alternative, the pins (not shown) can be spring-loaded and can be as press-studs with a positive return when turned to release.

Against these gland-ring locking members 15/30 contact the outward facing surface of the first retaining ring 17 which is the floating one, by passing around the girth of the log. This floating ring 17 is formed of a rigid material preferably in a form that allows it to be passed about the girth of the log rather than passed over the end of the log. The form of the ring 17 consists of two hinged semicircular halves which can be passed around the logs girth and the two free ends of the two halves forced together to complete a ring about the log. Materials such as steel, aluminium, wood, e.g. plywood, can be used which can also be in the two hinged semicircular halves and furthermore can be cut so that its internal circumference substantially conforms to the contours of the log. Thus the floating ring 17 can be made to fit a log which has an end substantially deviating from circular in section. This first ring 17, floating," does not tightly contact the log as it is required to move freely in a longitudinal direction over the surface of the log abutted by the log-locking members 15/30 of the cap end.

The elastomeric self'sealing means which consists of the ring 18 in its relaxed state is of substantially incumbent U- or W-shaped cross-section, ie with a solid base having at least two arms extending therefrom. The base must have an extrudability character while the arms have an elasticity requirement. The sealing ring 18 can be made of a single material having the required ratio of elasticity to ductility but desirably it is envisaged the arms be made of material having sufficient elasticity for the purpose of expanding under pressure to fill almost entirely the void volume occupied by the sealing means, with the base being a more rigid material having a low ductility so that it does not extrude through any gaps that remain between the internal surface of the floating ring 17 and the surface of the log. The sealing ring 18 can be made with or without stretching to pass over the end of the log to provide a ring about the log which need not be of a tight fit. A means of improving the surface smoothness of the log where the sealing means is to be localised is to spread paste onto the surface of the log so as to form a smooth gap filling seal.

The second or fixed ring 19 is similar to the first or floating ring 18 but is of radial depth sufficient to substantially fill the space between the surface of the log and the internal surface of the cap 10, with true internal and outer surfaces and an angular radial crosssection to encompass the chain 20. A corner is of a ring half severed so that when opened the internal surface of the ring at the hinge joint is relatively flat, thus ensuring that a closer fit to the log can be achieved. The open ends are of similar construction but it is not so necessary to sever the corner in the join. Locking means for the mating ends can be a spring loaded ball (not shown) in one surface meeting with a notch in its mating surface or a pin (not shown) inserted through holes in the ring lugs similar to the hinge pin.

This second or fixed retaining ring 19 is basically of similar construction to the floating ring 17 and passes about the girth of the log but is fixed against longitudinal displacement in relation to the log by the retaining chain 20 which is firmly held against longitudinal movement on the log.

The retaining means consists of the linked chain 20, the order to closely conform to the contours ofa particular log. The chain, similar to motor-cycle drive chain, has been found to be satisfactory with the tightening means 29 to bring the chain into tight engagement with the log. The use of spikes on the chain is unnecessary so long as the chain can be pulled tightly and locked into such a tight position by a locking means which fits inside the cap, and does not prevent the cap being passed over the gland system. The chain conforms itself to the contours of the log and thus provides a fixture or backing for the fixed ring 19 and there is an even resis tance to displacement at all points along the chains length.

For operation the sealing ring 18 has first to be compressed before admitting the log-treating fluid under pressure into the fluid treatment zone defined between the second ring 19, the end log surface and the inside of cap and this is achieved by the log end pressure exerting or displacing ram 13. The cylinder 23 is connected by connections 14 to a suitable pressure supply such as oil or air under pressure, or alternatively a line can pass from the pressurised treating'fluid supply line.

The controlled air release valve 16 provided in the cap 10 has the float 26 which is operated by the level of the fluid in the cap during filling, will seal when there is still a small amount of air remaining in the cap. This avoids drips of treating fluid coming out of the valve before the float seals the valve.

Fluid pressure applied behind the piston 21 of the ram 13 urges the piston forward through a head 31 guided by the sleeves on the sleeve guide of the cylinder 23 to abut against the adjacent end of the log L and thus compresses the elastomeric sealing ring 18. There is provision for enough extension of the piston 21 so that the sealing ring is substantially compressed. Thus the head, sleeve and sleeve guide of the cylinder are provided to maintain the piston is a straight line position. The head 31 is attached to the sleeve guide cylinder in an easily removable manner, e.g. by screwing, in order that access to scaling O-rings 22 is simple for replacement purposes.

A hole 32 is provided in the head 31 in order that during the impregnation cycle the pressure of fluid is equalised on both sides of the head. The piston cylinder 23 is sealed through the cap wall to the fluid supply. Two valves 32 are interposed in the lines 14 to control the flow of fluid to and from the displacing ram 13.

Opening of one of the valves 32' allows fluid under pressure to enter the cylinder 23 which thus forces the piston 21 against the surface of the end of the log L. The force thus exerted on the log end causes the cap 10 to be displaced away from the end of the log. thus displacing the floating retaining ring 17 acted on by the locking members 15/30. The movement of the floating ring 17 causes further compression of the elastomeric sealing ring 18 between the faces of the floating and retaining rings 17, 19 and causing the ring 18 to fill substantially the volume of the space between the fixed and floating rings l9, 17, the log surface and the interior of the wall of the cap 10.

To achieve this result the elastomeric sealing ring 18 must be of a material having sufficient elasticity to conform to the shape of the sealing ring space but having sufficient rigidity so as not to extrude under the pressure exerted by the pressurized impregnating fluid. The most satisfactory materials have been found to be those having Tensile strength 800- l 200 psi Elasticity l25-l75% Hardness 2837 Suitable materials having such a property have been found to be natural rubber from Malaysia. A more preferred material is room temperature vulcanising silicone rubber, e.g. that sold under Trade Name Silicoset by Imperial Chemical Industries Limited, which silicone rubber can be cast in a mould to the shape required. A still more preferred material is rubber compounded to give the properties within the range stipu' lated above after being cast.

What is claimed is:

1. An apparatus for longitudinal fluid impregnation ofa log comprising a cap for enclosing one end of a log, the cap having a rear wall and a peripheral side wall so as to define a fluid treatment zone, locking members inserted through apertures in the side wall of the cap for slidably locking the cap to the log, a first ring for encircling the log and abutting the locking members, a compressible sealing means for encircling the log and abutting the first ring, a second ring for encircling the log and abutting the sealing means, means for preventing the second ring from moving toward said on end of the log, the first ring, the sealing means, the second ring and the preventing means respectively sequentially located on the log from the locking members toward said one end of the log to be located within the cap, ram means associated with said cap for exerting pressure on said one end of the log for longitudinally moving said locking members toward said one end of the log so that compression will be applied to the sealing means, and means for introducing a pressurized log-treating fluid into the treatment zone so that said fluid will be forced into the log.

2. An apparatus as claimed in claim 1 wherein the first ring consists of two hinged semicircular halves lockable together.

3. An apparatus as claimed in claim 1 wherein the sealing means in a non-compressed state is of substantially U- or W-shaped cross-section and the second ring is fixed and of a radial depth sufficient to substantially fill the space between the surface of a log and the internal surface of the cap.

4. An apparatus as claimed in claim 1 wherein the sealing means consists of a resilient sealing ring having properties so as to be resilient to compression but of sufficient elasticity to be capable of stretching and filling the space the sealing ring occupies.

5. An apparatus as claimed in claim 1 wherein the preventing means includes a chain having a length for passing around the girth of a log and a locking means for securing the chain tightly on the log.

6. An apparatus as claimed in claim I wherein the rear wall of the cap consists of a rigid, impermeable substantially half-spherical, closed end pressure vessel and the side wall of the cap consists of a cylindrical body open at one end.

7. An apparatus as claimed in claim 6 wherein a line ending in a gauze filter is connected to said introducing means for admitting fluid to the bottom of the cap.

8. An apparatus as claimed in claim 1 wherein the ram means consists of a hydraulic piston mounted through the rear wall of the cap, said ram means having fluid-line inlet and outlet connections, and wherein said locking members include locking pins mounted through the cap near the open end thereof, and wherein said cap further includes an air release valve mounted through the cap near the rear wall thereof on a vertical axis.

9. An apparatus as claimed in claim 8 wherein the piston passes through a head of a piston cylinder to abut an adjacent end of a log when located in the cap, the head having a hole for equalizing fluid pressure on both sides of the head, and wherein valves are interposed in the fluid-line connections of said ram means for controlling fluid flow.

10. An apparatus as claimed in claim 8 wherein the air release valve in a float type valve having a float and a valve ring, said float so balanced that when it is immersed in the fluid it sits on said valve ring for closing the valve and allowing the build-up of hydraulic pressure, the float being positioned slightly below the inside surface of the cap so that the valve shuts before the fluid in the cap reaches the valve ring.

11. An apparatus as claimed in claim 8 wherein the first ring which is a loose ring, the sealing means, the second ring which is a fixed ring constitute a gland system and the preventing means consists of a chain to encircle the girth of the log and fixed to the log.

12. An apparatus as claimed in claim 11 wherein the chain has a tightening device for securing the chain to the log.

13. An apparatus as claimed in claim 8 wherein the locking pins are evenly spaced and arranged substantially in a plane around the girth of a log and removably passing through apertures near the open end of the cap, to slidably contact the log.

14. An apparatus as claimed in claim 13, wherein the pins are quick-release bayonet screws.

15, An apparatus as claimed in claim 13 wherein the pins are spring-loaded press-studs. 

1. An apparatus for longitudinal fluid impregnation of a log comprising a cap for enclosing one end of a log, the cap having a rear wall and a peripheral side wall so as to define a fluid treatment zone, locking members inserted through apertures in the side wall of the cap for slidably locking the cap to the log, a first ring for encircling the log and abutting the locking members, a compressible sealing means for encircling the log and abutting the first ring, a second ring for encircling the log and abutting the sealing means, means for preventing the second ring from moving toward said on end of the log, the first ring, the sealing means, the second ring and the preventing means respectively sequentially located on the log from the locking members toward said one end of the log to be located within the cap, ram means associated with said cap for exerting pressure on said one end of the log for longitudinally moving said locking members toward said one end of the log so that compression will be applied to the sealing means, and means for introducing a pressurized log-treating fluid into the treatment zone so that said fluid will be forced into the log.
 2. An apparatus as claimed in claim 1 wherein the first ring consists of two hinged semicircular halves lockable together.
 3. An apparatus as claimed in claim 1 wherein the sealing means in a non-compressed state is of substantially U- or W-shaped cross-section and the second ring is fixed and of a radial depth sufficient to substantially fill the space between the surface of a log and the internal surface of the cap.
 4. An apparatus as claimed in claim 1 wherein the sealing means consists of a resilient sealing ring having properties so as to be resilient to compression but of sufficient elasticity to be capable of stretching and filling the space the sealing ring occupies.
 5. An apparatus as claimed in claim 1 wherein the preventing means includes a chain having a length for passing around the girth of a log and a locking means for securing the chain tightly on the log.
 6. An apparatus as claimed in claim 1 wherein the rear wall of the cap consists of a rigid, impermeable substantially half-spherical, closed end pressure vessel and the side wall of the cap consists of a cylindrical body open at one end.
 7. An apparatus as claimed in claim 6 wherein a line ending in a gauze filter is connected to said introducing means for admitting fluid to the bottom of the cap.
 8. An apparatus as claimed in claim 1 wherein the ram means consists of a hydraulic piston mounted through the rear wall of the cap, said ram means having fluid-line inlet and outlet connections, and wherein said locking members include locking pins mounted through the cap near the open end thereof, and wherein said cap further includes an air release valve mounted through the cap near the rear wall thereof on a vertical axis.
 9. An apparatus as claimed in claim 8 wherein the piston passes through a head of a piston cylinder to abut an adjacent end of a log when located in the cap, the head having a hole for equalizing fluid pressure on both sides of the head, and wherein valves are interposed in the fluid-line connections of said ram means for controlling fluid flow.
 10. An apparatus as claimed in claim 8 wherein the air release valve in a float type valve having a float and a valve ring, said float so balanced that when it is immersed in the fluid it sits on said valve ring for closing tHe valve and allowing the build-up of hydraulic pressure, the float being positioned slightly below the inside surface of the cap so that the valve shuts before the fluid in the cap reaches the valve ring.
 11. An apparatus as claimed in claim 8 wherein the first ring which is a loose ring, the sealing means, the second ring which is a fixed ring constitute a gland system and the preventing means consists of a chain to encircle the girth of the log and fixed to the log.
 12. An apparatus as claimed in claim 11 wherein the chain has a tightening device for securing the chain to the log.
 13. An apparatus as claimed in claim 8 wherein the locking pins are evenly spaced and arranged substantially in a plane around the girth of a log and removably passing through apertures near the open end of the cap, to slidably contact the log.
 14. An apparatus as claimed in claim 13, wherein the pins are quick-release bayonet screws.
 15. An apparatus as claimed in claim 13 wherein the pins are spring-loaded press-studs. 